﻿#include "util.hpp"
// AES为分组密码,分组密码也就是把明文分成一组一组的,每组长度相等,每次加密一组数据,
// 直到加密完整个明文。在AES标准规范中,分组长度只能是128位,
// 也就是说,每个分组为16个字节（每个字节8位）。
// 密钥的长度可以使用128位、192位或256位。密钥的长度不同,推荐加密轮数也不同
// 这里我们实现AES128 密钥长度 4*32 分组长度 4*32 加密轮数 10

const int DECODE_MODE = 0;
const int ENCODE_MODE = 1;
const int ROUNDS = 10;

// 定义S盒
const static unsigned char S[16][16] =
{
	{ 0x63 ,0x7c ,0x77 ,0x7b ,0xf2 ,0x6b ,0x6f ,0xc5 ,0x30 ,0x01 ,0x67 ,0x2b ,0xfe ,0xd7 ,0xab ,0x76 ,},
	{ 0xca ,0x82 ,0xc9 ,0x7d ,0xfa ,0x59 ,0x47 ,0xf0 ,0xad ,0xd4 ,0xa2 ,0xaf ,0x9c ,0xa4 ,0x72 ,0xc0 ,},
	{ 0xb7 ,0xfd ,0x93 ,0x26 ,0x36 ,0x3f ,0xf7 ,0xcc ,0x34 ,0xa5 ,0xe5 ,0xf1 ,0x71 ,0xd8 ,0x31 ,0x15 ,},
	{ 0x04 ,0xc7 ,0x23 ,0xc3 ,0x18 ,0x96 ,0x05 ,0x9a ,0x07 ,0x12 ,0x80 ,0xe2 ,0xeb ,0x27 ,0xb2 ,0x75 ,},
	{ 0x09 ,0x83 ,0x2c ,0x1a ,0x1b ,0x6e ,0x5a ,0xa0 ,0x52 ,0x3b ,0xd6 ,0xb3 ,0x29 ,0xe3 ,0x2f ,0x84 ,},
	{ 0x53 ,0xd1 ,0x00 ,0xed ,0x20 ,0xfc ,0xb1 ,0x5b ,0x6a ,0xcb ,0xbe ,0x39 ,0x4a ,0x4c ,0x58 ,0xcf ,},
	{ 0xd0 ,0xef ,0xaa ,0xfb ,0x43 ,0x4d ,0x33 ,0x85 ,0x45 ,0xf9 ,0x02 ,0x7f ,0x50 ,0x3c ,0x9f ,0xa8 ,},
	{ 0x51 ,0xa3 ,0x40 ,0x8f ,0x92 ,0x9d ,0x38 ,0xf5 ,0xbc ,0xb6 ,0xda ,0x21 ,0x10 ,0xff ,0xf3 ,0xd2 ,},
	{ 0xcd ,0x0c ,0x13 ,0xec ,0x5f ,0x97 ,0x44 ,0x17 ,0xc4 ,0xa7 ,0x7e ,0x3d ,0x64 ,0x5d ,0x19 ,0x73 ,},
	{ 0x60 ,0x81 ,0x4f ,0xdc ,0x22 ,0x2a ,0x90 ,0x88 ,0x46 ,0xee ,0xb8 ,0x14 ,0xde ,0x5e ,0x0b ,0xdb ,},
	{ 0xe0 ,0x32 ,0x3a ,0x0a ,0x49 ,0x06 ,0x24 ,0x5c ,0xc2 ,0xd3 ,0xac ,0x62 ,0x91 ,0x95 ,0xe4 ,0x79 ,},
	{ 0xe7 ,0xc8 ,0x37 ,0x6d ,0x8d ,0xd5 ,0x4e ,0xa9 ,0x6c ,0x56 ,0xf4 ,0xea ,0x65 ,0x7a ,0xae ,0x08 ,},
	{ 0xba ,0x78 ,0x25 ,0x2e ,0x1c ,0xa6 ,0xb4 ,0xc6 ,0xe8 ,0xdd ,0x74 ,0x1f ,0x4b ,0xbd ,0x8b ,0x8a ,},
	{ 0x70 ,0x3e ,0xb5 ,0x66 ,0x48 ,0x03 ,0xf6 ,0x0e ,0x61 ,0x35 ,0x57 ,0xb9 ,0x86 ,0xc1 ,0x1d ,0x9e ,},
	{ 0xe1 ,0xf8 ,0x98 ,0x11 ,0x69 ,0xd9 ,0x8e ,0x94 ,0x9b ,0x1e ,0x87 ,0xe9 ,0xce ,0x55 ,0x28 ,0xdf ,},
	{ 0x8c ,0xa1 ,0x89 ,0x0d ,0xbf ,0xe6 ,0x42 ,0x68 ,0x41 ,0x99 ,0x2d ,0x0f ,0xb0 ,0x54 ,0xbb ,0x16 ,}
};

// 逆S盒子
const static unsigned char SD[16][16] =
{
	{ 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb },
	{ 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb },
	{ 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e },
	{ 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25 },
	{ 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92 },
	{ 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84 },
	{ 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06 },
	{ 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b },
	{ 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73 },
	{ 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e },
	{ 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b },
	{ 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4 },
	{ 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f },
	{ 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef },
	{ 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61 },
	{ 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d }
};

// 定义列变换 混淆矩阵
const static unsigned char Confusion[4][4] =
{
	{ 0x02, 0x03, 0x01, 0x01 },
	{ 0x01, 0x02, 0x03, 0x01 },
	{ 0x01, 0x01, 0x02, 0x03 },
	{ 0x03, 0x01, 0x01, 0x02 }
};

// 定义密钥拓展时 使用到的常量矩阵
const static unsigned char Rcon[ROUNDS][4] =
{
	{ 0x01, 0x00, 0x00, 0x00 },
	{ 0x02, 0x00, 0x00, 0x00 },
	{ 0x04, 0x00, 0x00, 0x00 },
	{ 0x08, 0x00, 0x00, 0x00 },
	{ 0x10, 0x00, 0x00, 0x00 },
	{ 0x20, 0x00, 0x00, 0x00 },
	{ 0x40, 0x00, 0x00, 0x00 },
	{ 0x80, 0x00, 0x00, 0x00 },
	{ 0x1B, 0x00, 0x00, 0x00 },
	{ 0x36, 0x00, 0x00, 0x00 }
};




// 通过 S 盒替换字节
// 0001 0010
// 0001
unsigned char ChangeByteByS(const unsigned char item)
{
	// 对于算数移位 右移符号位不变 填充符号位 而不是填充0 
	// 不同的编译器和平台处理不同 为了防止出现意外 这里进行处理 去掉高位
	unsigned char left = ((item & 0xf0) >> 4) & 0x0f;
	// 对于 right 不需要去移位 直接可以得到
	unsigned char right = item & 0x0f;
	return S[left][right];
}





//对W数组扩充40个新列,构成总共44列的扩展密钥数组。新列以如下的递归方式产生：
//1.如果i不是4的倍数,那么第i列由如下等式确定：
//W[i] = W[i - 4]⨁W[i - 1]
//2.如果i是4的倍数,那么第i列由如下等式确定：
//W[i] = W[i - 4]⨁T(W[i - 1])

void Nand(const unsigned char* a, const unsigned char* b, unsigned char* dest)
{
	for (unsigned char pos = 0; pos < 4; ++pos)
	{
		dest[pos] = a[pos] ^ b[pos];
	}
}

void ShiftRow(unsigned char* contents, const int mode)
{
	for (char i = 1; i < 4; ++i)
	{
		unsigned char tmp[4] = { 0 };
		memcpy(tmp, contents + 4 * i, sizeof(unsigned char) * 4);
		for (char j = 0; j < 4; ++j)
		{
			if (ENCODE_MODE == mode)
			{
				if (j - i < 0)
				{
					contents[4 * i + 4 + j - i] = tmp[j];
				}
				else
				{
					contents[4 * i + j - i] = tmp[j];
				}
			}
			else if (DECODE_MODE == mode)
			{
				if (j + i >= 4)
				{
					contents[4 * i - 4 + j + i] = tmp[j];
				}
				else
				{
					contents[4 * i + j + i] = tmp[j];
				}
			}
		}
	}
}

// 置换
void ReplaceArr(unsigned char* content, const int mode)
{
	unsigned char tmp[16] = { 0 };
	memcpy(tmp, content, sizeof(unsigned char) * 16);
	for (unsigned char i = 0; i < 16; ++i)
	{
		unsigned left = (tmp[i] >> 4) & 0x0f;
		unsigned right = (tmp[i]) & 0x0f;
		if (ENCODE_MODE == mode)
		{
			content[i] = S[left][right];
		}
		else if (DECODE_MODE == mode)
		{
			content[i] = SD[left][right];
		}
	}
}


unsigned char GaloisMultiplication(unsigned char Num_L, unsigned char Num_R)
{
	//定义变量
	unsigned char Result = 0;       //伽罗瓦域内乘法计算的结果

	while (Num_L)
	{
		//如果Num_L最低位是1就异或Num_R，相当于加上Num_R * 1
		if (Num_L & 0x01)
		{
			Result ^= Num_R;
		}

		//Num_L右移一位，相当于除以2
		Num_L = Num_L >> 1;

		//如果Num_R最高位为1
		if (Num_R & 0x80)
		{
			//左移一位相当于乘二
			Num_R = Num_R << 1;
			//计算伽罗瓦域内除法Num_R = Num_R / (x^8(刚好丢失最高位) + x^4 + x^3 + x^1 + 1)
			Num_R ^= 0x1B;
		}
		else
		{
			//左移一位相当于乘二
			Num_R = Num_R << 1;
		}
	}
	return Result;

}

const unsigned char MixArray[4][4] =
{
	{ 0x02, 0x03, 0x01, 0x01 },
	{ 0x01, 0x02, 0x03, 0x01 },
	{ 0x01, 0x01, 0x02, 0x03 },
	{ 0x03, 0x01, 0x01, 0x02 }
};

const unsigned char MixArrayD[4][4] =
{
	{ 0x0e, 0x0b, 0x0d, 0x09 },
	{ 0x09, 0x0e, 0x0b, 0x0d },
	{ 0x0d, 0x09, 0x0e, 0x0b },
	{ 0x0b, 0x0d, 0x09, 0x0e }
};


void MixColumns(unsigned char* content, const int mode)
{
	unsigned char tmp[16] = { 0 };
	memcpy(tmp, content, sizeof(unsigned char) * 16);

	//矩阵乘法 4*4
	for (int i = 0; i < 4; i++)
	{
		for (int j = 0; j < 4; j++)
		{
			if (ENCODE_MODE == mode)
			{
				content[i * 4 + j] =
					GaloisMultiplication(MixArray[i][0], tmp[j]) ^
					GaloisMultiplication(MixArray[i][1], tmp[4 + j]) ^
					GaloisMultiplication(MixArray[i][2], tmp[8 + j]) ^
					GaloisMultiplication(MixArray[i][3], tmp[12 + j]);
			}
			else
			{
				content[i * 4 + j] =
					GaloisMultiplication(MixArrayD[i][0], tmp[j]) ^
					GaloisMultiplication(MixArrayD[i][1], tmp[4 + j]) ^
					GaloisMultiplication(MixArrayD[i][2], tmp[8 + j]) ^
					GaloisMultiplication(MixArrayD[i][3], tmp[12 + j]);
			}

		}
	}
}


// pos 轮数
void T(unsigned char* source, unsigned char pos)
{
	// 1. 循环左移
	// 2. 字节代换
	unsigned char tmp[4] = { ChangeByteByS(*(source + 1)), ChangeByteByS(*(source + 2)), ChangeByteByS(*(source + 3)), ChangeByteByS(*(source)) };
	// 3. 常量异或
	Nand(tmp, Rcon[pos - 1], source);
}

void WheelKeyMultiplication(unsigned char* content, unsigned char* key)
{
	for (unsigned char i = 0; i < 4; ++i)
	{
		content[i] ^= key[4 * i];
		content[4 + i] ^= key[4 * i + 1];
		content[8 + i] ^= key[4 * i + 2];
		content[12 + i] ^= key[4 * i + 3];

	}
}




void _AES(unsigned char* content, unsigned char* key, const unsigned char len, const int mode)
{
	// 0.构建明文矩阵
	unsigned char source[20] = { 0 };
	memcpy(source, content, sizeof(unsigned char) * 16);
	if (ENCODE_MODE == mode)
	{
		// 1. 填充矩阵 顺便字节替换
		ReplaceArr(source, mode);
		// 2. 行位移
		ShiftRow(source, mode);
		// 3. 列混合 注意最后一次不需要列混合
		if (len != 10)
		{
			MixColumns(source, mode);
		}
		// 4. 轮密钥加
		WheelKeyMultiplication(source, key);
	}
	else if (DECODE_MODE == mode)
	{

		// 1. 逆行位移
		ShiftRow(source, mode);
		// 2. 字节替换
		ReplaceArr(source, mode);
		// 3. 轮密钥加
		WheelKeyMultiplication(source, key);
		// 4. 列混合 注意最后一次不需要列混合
		if (len != 10)
		{
			MixColumns(source, mode);
		}


	}
	// 5. 回放
	for (size_t i = 0; i < 16; ++i)
	{
		content[i] = source[i];
	}

}


void AESGetWheelKey(const std::string& key, unsigned char* wheelKey)
{
	/// std::string test("abcdefghijklmnop");
	unsigned char keyArr[16] = { 0 };
	for (size_t j = 0; j < 16; ++j)
	{
		keyArr[j] = key[j];
	}
	memcpy(wheelKey, keyArr, sizeof(unsigned char) * 16);
	// 生成轮密钥
	for (unsigned char pos = 4; pos < 44; ++pos)
	{
		if (pos % 4 == 0)
		{
			unsigned char tmp[4] = { wheelKey[(pos - 1) * 4], wheelKey[(pos - 1) * 4 + 1], wheelKey[(pos - 1) * 4 + 2], wheelKey[(pos - 1) * 4 + 3] };
			T(tmp, pos / 4);
			Nand(wheelKey + (pos - 4) * 4, tmp, wheelKey + pos * 4);
		}
		else
		{
			Nand(wheelKey + (pos - 4) * 4, wheelKey + (pos - 1) * 4, wheelKey + pos * 4);
		}
	}

}

std::string AES(const std::string& word, const std::string& key, const int mode)
{

	unsigned char wheelKey[176] = { 0 };
	AESGetWheelKey(key, wheelKey);
	// 生成内容矩阵
	unsigned char content[16] = { 0 };
	for (size_t j = 0; j < 4; ++j)
	{
		content[j] = word[j * 4];
		content[4 + j] = word[j * 4 + 1];
		content[8 + j] = word[j * 4 + 2];
		content[12 + j] = word[j * 4 + 3];
	}

	// 先进行一轮轮密钥相加 然后进入10次轮转
	if (ENCODE_MODE == mode)
	{
		WheelKeyMultiplication(content, wheelKey);
	}
	else if (DECODE_MODE == mode)
	{
		WheelKeyMultiplication(content, wheelKey + 160);
	}

	// 10 次轮转
	for (unsigned char pos = 0; pos < 10; ++pos)
	{
		if (ENCODE_MODE == mode)
		{
			_AES(content, wheelKey + 16 * (pos + 1), pos + 1, mode);
		}
		else if (DECODE_MODE == mode)
		{
			_AES(content, wheelKey + 144 - pos * 16, pos + 1, mode);
		}
	}
	// 包装为字符串进行返回
	char result[16] = { 0 };
	for (size_t j = 0; j < 4; ++j)
	{
		result[j * 4] = (char)(content[j]);
		result[j * 4 + 1] = (char)(content[4 + j]);
		result[j * 4 + 2] = (char)(content[8 + j]);
		result[j * 4 + 3] = (char)(content[12 + j]);
	}
	std::cout << "AES(BASE64): " << base64_encode((unsigned char*)result, 16) << std::endl;
	std::string str;
	for (size_t j = 0; j < 16; ++j)
	{
		str += result[j];
	}
	return str;
}

